DNS
3 10 Local Cache. (n.d.). Retrieved March 10, 2015, from http://docs.oracle.com/cd/E24290_01/coh.371/e22840/localcache.htm#COHGS233[3] 10 Local Cache. (n.d.). Retrieved March 10, 2015, from http://docs.oracle.com/cd/E24290_01/coh.371/e22840/localcache.htm#COHGS233[2] Brain, M., & Crawford, S. (n.d.). How Domain Name Servers Work - HowStuffWorks. Retrieved March 7, 2015, from http://computer.howstuffworks.com/dns.htm'OVERVIEW'1 Gonyea, C. (2010, August 25). DNS: Why It’s Important & How It Works. Retrieved March 7, 2015, from http://dyn.com/blog/dns-why-its-important-how-it-works/ Domain Name Server (DNS) is a system for changing a domain name into an IP (internet protocol) address. A domain name is a user-friendly name like www.google.com. Machines however use numbers instead of letters to locate website pages. The domain name server changes a domain name into a set of numbers that your computer can read. These are called IP addresses. An example of an IP address is 173.194.43.83. ' HOW DOES DNS WORK?' DNS has a six-step process. Often all six steps are not completed because the information can be gathered in one or two steps. Step 1 The first step begins when you look up a domain name. The first thing your computer does is look in its local DNS cache. This stores information about websites you have recently visited. 1 The local cache is size limited. Therefore, when it becomes full, websites will be deleted. As well, a website can be time-limited. Meaning an expiration date is put on the website for how long it will stay in the local cache.3 Step 2 ' '''If the information is not in the local DNS cache, your computer will then contact your recursive DNS server. Your internet service provider will often operate Recursive DNS servers. Alternatively, you may be using a privately owned third party Recursive DNS server. 4 Recursive Dns servers have their own cache and the process normally ends here. '''Step 3' ' '''If the recursive DNS servers do not have the information, your computer asks the root name server. The root name server is a computer that can direct the computer to somewhere where they can find the unknown IP address. '''Step 4' ' '''Next, the computer asks the Authoritative name server that the root nameserver directed us to. An authoritative name server knows all the information about a specific domain. These are stored in DNS records. Many types of DNS records exist, to find an IP address you would look for an A record. The recursive DNS server will then recover the proper file. '''Step 5' ' '''The recursive server will then retrieve the information from the authoritative name server and store it in its local cache. '''Step 6' ' '''Finally, the recursive server will return the record back to your computer. Your computer will then store the record in its local cache temporarily and read the IP address, and gives the information to your web browser. This entire process takes only a few milliseconds to complete. 1 '''Who uses it?' Anyone who uses the internet will indirectly use DNS. Although it will not be used directly as, it is a program that runs in the background. Where is it used? ''' DNS can be used anywhere, the only requirement is that there is an internet connection. '''Difficulty use As DNS is used indirectly, it is very simple to use. However there can be errors that make it slightly more difficult to use. Some errors can be caused by poor internet connection, or the DNS server stops responding. Often these errors will resolve themselves after a few minutes, however it can be frustrating. So I rate DNS as a 9 out of 10 difficulty level. QUESTIONS 1. How many steps are involved in retrieving information from the recursive DNS server? a) 2 b) 6 c) 7 Answer: a 2. What is the local cache? a) A server with all the information about one domain b) A server that translates a website name into an IP address c) A cache with the IP addresses of websites you have recently visited. Answer: c''' '''3. Who uses DNS? a) Computer programmers b) All Internet users c) Government officials Answer: b 4. What does IP stand for a) Internet Provider b) Internet Protocol c) Inspection Procedure Answer: b 5. What does DNS stand for? a) Domain name server b) Data network services c) Dynamic name server Answer: a 6. When do you use DNS? a) When you search a website name b) When you use Microsoft word c) Only when you search historical dates Answer: a 7. Is DNS difficult to use? a) Yes b) No c) Only if you do not have the proper software installed Answer: a 8. How many steps are involved in contacting the root name server? a) 3 b) 5 c) 2 Answer: a 9. What is the Authoritative name server? a) A server that stores information for your computer b) A set of steps involved in finding IP addresses c) A server responsible for all information about one domain Answer: c 10. What does DNS do? a) Make suggestions on how to fix internet problems b) Changes website names into an IP address c) Downloads files onto your computer Answer: b 1 Gonyea, C. (2010, August 25). DNS: Why It’s Important & How It Works. Retrieved March 7, 2015, from http://dyn.com/blog/dns-why-its-important-how-it-works/ 2 Brain, M., & Crawford, S. (n.d.). How Domain Name Servers Work - HowStuffWorks. Retrieved March 7, 2015, from http://computer.howstuffworks.com/dns.htm 3 10 Local Cache. (n.d.). Retrieved March 10, 2015, from http://docs.oracle.com/cd/E24290_01/coh.371/e22840/localcache.htm#COHGS233 4 Goguen, N. (2013, November 22). Authoritative DNS Servers vs. Recursive DNS Servers - No-IP Blog - Managed DNS Services. Retrieved March 10, 2015, from http://www.noip.com/blog/2013/11/22/authoritative-dns-vs-recursive-dns-work/